Which probiotics are actually clean and still alive?

Almost every probiotic sells itself on one big number, the CFU count on the front of the box, and that number is the least reliable thing on the label, because it is usually measured at the factory and says nothing about strains, testing, or fillers. These steps put the highest-signal checks first, so you can shop for proof instead of billions. Start with whether the count is guaranteed through the expiration date, then move to strain-level naming, independent verification, potency units, and the filler and allergen list. Because probiotics are regulated as supplements rather than drugs, the FDA does not verify these claims before a product reaches the shelf, so the burden of proof sits with the brand and with you.

1. 1

   Start with a CFU count guaranteed through expiration

   The single most useful line on a probiotic label is the one most brands leave off: a CFU count guaranteed through the expiration date, not at the time of manufacture. Live cultures die in the bottle, so a factory count tells you little about the dose you actually get, which is why the NIH Office of Dietary Supplements advises choosing products that guarantee the count through the end of shelf life. Nature's Way Fortify Adults 50+ does this with 50 billion cultures and scored 5.1, while Align guarantees 1 billion at manufacture but only 10 million by its best-by date. Make this your first filter.

2. 2

   Check for the strain, not just the genus

   The next thing to check is whether the label names the actual strain, not only the genus and species. The International Scientific Association for Probiotics and Prebiotics states that a probiotic's benefits are strain-specific, so the research only applies if you know the exact strain in the bottle. Culturelle names Lactobacillus rhamnosus GG, one of the most-studied strains, and scored 4.9. VSL#3 packs 112.5 billion cultures but lists only species, so you cannot match its organisms to the studies. A big count of unnamed strains is billions you cannot verify.

3. 3

   Ask whether anyone independent checked the count

   After strains, ask whether an outside lab has verified the count actually in the bottle, because this is where the label and reality tend to part ways. ConsumerLab testing has found some probiotics with less than half their labeled organisms, one with only 14 million viable cells. Independent lab Labdoor measured Garden of Life Raw Probiotics Kids at about 2.4 billion viable cells against a 5 billion label, roughly 53 percent under, which is part of why it scored 2.9. A number no one has checked is a marketing claim, not a dose.

4. 4

   Treat a third-party tested claim as unverified until you see the result

   Be careful with the phrase third-party tested, because a claim is not a result, and several brands say they test but never publish the numbers you would need to check. Renew Life Extra Care 50B scored 3.8 and Physician's Choice 60 Billion scored 3.0, and both rest on a third-party testing claim with no published report. The brands worth extra trust are the ones that show you the actual test, and in this category none of the nine published a heavy-metal result at all. Treat an unpublished claim as unverified rather than as proof.

5. 5

   Know that AFU is not the same as CFU

   Watch for units that quietly change the comparison. Seed DS-01 labels its potency as 53.6 billion AFU, active fluorescent units, rather than CFU, colony forming units, and the two are not directly comparable, so a bigger AFU number does not mean more live culture than a smaller CFU one. Seed does name all 24 of its strains, which earned real credit and a 3.9, but the unit switch means you cannot line it up against a CFU-labeled bottle. When the unit is unusual, compare within the same unit or not at all.

6. 6

   Read the inactive ingredient list, not just the culture count

   The culture count says nothing about what surrounds it, so read the inactive ingredients too. Fillers and flow agents like magnesium stearate and maltodextrin show up in many capsules, and some brands add colorants a probiotic does not need. Align 24/7 adds titanium dioxide, a whitening colorant that does nothing for gut health, and scored 2.5. If you are buying for a kid or a sensitive stomach, a shorter, cleaner inactive list is worth more than a higher number on the front.

7. 7

   Match the format to how you will actually store it

   Finally, match the format to your routine, because some high-count probiotics only hold their cultures cold. VSL#3 at 112.5 billion cultures and Garden of Life Raw Probiotics Kids are both refrigerated, which protects potency but means the bottle cannot sit in a warm cabinet or travel in a bag. A shelf-stable product is more forgiving, as long as its guaranteed-through-expiration count already accounts for room-temperature storage. Buy the format that fits your real life, not the one that looks strongest on the shelf.